The present invention relates to saws, such as chop saws, miter saws and flip over saws, and in particular relates to saws comprising a table and a saw assembly carrying a motor driven saw blade which is pivotally mounted on the table such that the saw assembly can be lowered towards the table to plunge the saw blade into a workpiece, resting on the table.
Such saws generally have a fixed upper saw blade guard covering the upper part of the saw blade and a moveable lower saw blade guard for selectively exposing the saw blade when a cut is to be made in a workpiece and otherwise for protecting the user from the lower part of the saw blade. It is desirable when the saw is not in use, for example when it is transported from one work site to another, that the lower blade guard is locked closed so that the saw blade is protected by the upper and lower guards. However, when the saw is in use and its saw assembly is lowered towards the saw table, the lower blade guard should be unlocked and free to open to expose the saw blade so that the saw blade can make a cut in a workpiece.
A known guard lock arrangement is known from German patent application DE 197 43 498. This application relates to a locking mechanism in which the moveable lower guard of the saw is locked against movement which would expose the saw blade by a locking pin. The on-off switch for the motor of the saw is activated by a trigger element on the handle of the saw, which trigger element co-operates with a lock-off lever actuated by a release knob. The lock-off lever prevents movement of the trigger element so that the saw cannot be operated. The release knob is activated to move the lock-off lever into a position in which the trigger element can be depressed to switch on the motor. This activation of the release knob also releases the locking pin via a moveable articulated linkage arrangement so that the lower guard can be retracted when the saw assembly is lowered towards the saw table. This arrangement requires numerous moving parts which co-operate to unlock the guard when the lock-off lever is released by actuation of the release knob. As such the arrangement is quite complicated and after prolonged use of the saw can become vulnerable to the ingress of dust created by use of the saw, which dust can block the operation of the guard lock arrangement making it difficult for a user to operate.
Accordingly the present invention aims to provide a simplified guard lock arrangement which requires fewer moving parts than known arrangements and which accordingly is less vulnerable to becoming blocked or difficult to operate due to the ingress of dust.
According to the present invention there is provided a saw comprising a saw assembly comprising an upper saw blade guard and a motor which can be actuated by an on-off switch arrangement and can rotatingly drive a saw blade mounted on the assembly, which saw assembly is pivotably mounted on a saw table such that the saw assembly can be lowered towards the table to cut a workpiece resting on the table, a lower moveable guard which is mounted to the upper guard so that the lower guard is moveable to expose a saw blade mounted on the assembly, a guard lock arrangement operable by a user of the saw for locking the lower guard over a saw blade mounted on the saw assembly when the saw is not in use, where the guard lock arrangement comprises a guard lock lever which is moveably mounted to the saw assembly and comprises a locking portion and a switch actuation portion such that in an off-position of the guard lock lever the locking portion engages the lower guard to prevent it from moving and in an on-position of the guard lock lever the locking portion is disengaged from the lower guard so that the lower guard is free to move to expose the saw blade and the switch actuation portion engages the on-off switch arrangement.
In this way a single moveable part, the guard lock lever, is used to releasably lock the lower guard and to actuate the on-off switch arrangement of the motor. This provides a much simplified guard lock arrangement which reduces the number of components required in a saw of this type. Furthermore, the use of fewer moving parts makes the guard lock arrangement less vulnerable to the ingress of dust created when the saw is in use.
If the guard lock lever is mounted on the inside of the housing of the saw assembly so that the part of the lever which is accessed by a user extends outside of the housing through a hole in the housing, dust can enter the housing through this hole and infiltrate components located within the housing. Therefore, it is preferred that the guard lock lever according to the present invention is mounted on the outside of the saw assembly. For convenient actuation by a user of the saw the guard lock lever is preferably mounted on a handle provided on the saw assembly which handle is used by a user to lower the saw assembly towards the saw table.
In a preferred embodiment the guard lock lever is pivotally mounted to the saw assembly and preferably the switch actuation portion is located at a first end of the guard lock lever and the guard lock lever is pivotally mounted on the saw assembly at a second opposite end of the guard lock lever. More preferably, the guard lock lever is L-shaped and the locking portion extends from the bend in the guard lock lever.
The locking portion of the guard lock lever can simply comprise a latch extension which is engageable with a co-operating latch means on the lower blade guard. The co-operating latch means on the lower blade guard may simply comprise a recess formed in the lower blade guard.